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// Copyright 2017 The PDFium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <vector>
#include "core/fxcodec/gif/cfx_lzwdecompressor.h"
#include "third_party/base/numerics/safe_conversions.h"
// Between 2x and 5x is a standard range for LZW according to a quick
// search of papers. Running up to 10x to catch any niche cases.
constexpr uint32_t kMinCompressionRatio = 2;
constexpr uint32_t kMaxCompressionRatio = 10;
void LZWFuzz(const uint8_t* src_buf,
size_t src_size,
uint8_t color_exp,
uint8_t code_exp) {
std::unique_ptr<CFX_LZWDecompressor> decompressor =
CFX_LZWDecompressor::Create(color_exp, code_exp);
if (!decompressor)
return;
for (uint32_t compressions_ratio = kMinCompressionRatio;
compressions_ratio <= kMaxCompressionRatio; compressions_ratio++) {
std::vector<uint8_t> dest_buf(compressions_ratio * src_size);
// This cast should be safe since the caller is checking for overflow on
// the initial data.
uint32_t dest_size = static_cast<uint32_t>(dest_buf.size());
if (CFX_GifDecodeStatus::InsufficientDestSize !=
decompressor->Decode(const_cast<uint8_t*>(src_buf), src_size,
dest_buf.data(), &dest_size))
return;
}
}
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
// Need at least 3 bytes to do anything.
if (size < 3)
return 0;
// Normally the GIF would provide the code and color sizes, instead, going
// to assume they are the first two bytes of data provided.
uint8_t color_exp = data[0];
uint8_t code_exp = data[1];
const uint8_t* lzw_data = data + 2;
uint32_t lzw_data_size = static_cast<uint32_t>(size - 2);
// Check that there isn't going to be an overflow in the destination buffer
// size.
if (lzw_data_size >
std::numeric_limits<uint32_t>::max() / kMaxCompressionRatio) {
return 0;
}
LZWFuzz(lzw_data, lzw_data_size, color_exp, code_exp);
return 0;
}
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